The Ruy Lopez
This is a comprehensive analysis of the Ruy Lopez covering as much as possible and will keep getting updated whenever I play this line online.
C66: The Old Steinitz Defence
The Steinitz Defence (also called the Old Steinitz Defence) (ECO C62), 3...d6, is solid but passive and cramped. Although the favourite of the first world champion Wilhelm Steinitz, and often played by world champions and expert defensive players Emanuel Lasker, José Capablanca, and occasionally by Vasily Smyslov, it largely fell into disuse after World War I, as its inherent passivity spurred a search for more active means of defending the Spanish. White can force Black to concede the strongpoint at e5 (see Tarrasch Trap), a significant but not fatal concession.
The deferred variant of this defence (3...a6 4.Ba4 d6) offers Black a freer position and is more popular.